Defecography is a real-time radiologic study of defecation or the passage of a bowel movement.  It is performed in the radiology department at Cedars Sinai.  As part of the test, a patient will be asked to drink some oral contrast so the small bowel can be seen on the X-ray. There will also be a special paste placed into the rectum to simulate a bowel movement.  The paste is also designed to be seen on X-ray.  This study will give anatomic information about possible blockage that can occur during a bowel movement and lead to incomplete passage of stool or even trapping of stool, which is expelled at a later point, leading to passive fecal soiling.